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Table 3 Age and age-standardised characteristics of breast cancer cases, Nurses' Health Study (1976 to 1996)

From: Comparison of molecular phenotypes of ductal carcinoma in situand invasive breast cancer

Risk factors

DCIS (n = 272)

Invasive (n = 2249)

Means

  

Age at diagnosis, y

57.9

57.3

Age at menopause, y

45.2

45.5

Age at menarche, y

12.3

12.4

Body mass index at age 18, kg/m2

20.9

21.0

Paritya

3.1

3.2

Age at first birtha, y

24.9

25.4

Alcohol, g/week

5.7

6.3

Frequency, %

  

Family history of breast cancer

19.0

13.3

Nulliparous

6.9

6.9

Premenopausal at diagnosis

22.4

20.8

Postmenopausal at diagnosis

76.2

77.2

Prior benign breast disease

57.0

44.8

Current postmenopausal hormone useb

37.3

31.9

Molecular Markers, %

  

ER positive

74.0

77.0

PR positive

59.9

64.4

HER2 positive

27.2

10.9

  1. aAmong parous women only. bAmong postmenopausal women only. DCIS, ductal carcinoma in situ; ER, oestrogen receptor; HER2, human epidermal growth factor receptor 2; PR, progesterone receptor.